I thought the following product was very interesting, definitely fault tolerant, cheap memory disks are coming to the masses. The Gigabyte's i-RAM, is basically a standard PCI card that can take 4 standard memory modules and turn them into a battery backed up disk.
Throw your derby log on one of these and autocommit write performance goes up 100-1000 fold. http://www.tomshardware.com/storage/20050907/index.html
